---
title: Migrate from Vert.x 3 to Vert.x 4
category: guides
authors:
  - name: Julien Viet
    github_id: vietj
summary: >-
  We provide a clear and well-documented migration path from Vert.x 3.9 to Vert.x 4.
  Existing users will feel at home with the new version.
pinned: true
---

Vert.x 4 extends the Vert.x 3 line with a set of new features while providing the same Vert.x 3 experience: Vert.x 3
users will feel at home with Vert.x 4.

## Migration

Vert.x 4 has been developed with migration from Vert.x 3 in mind.

Vert.x 4 improves asynchronous programming with futures, however the callback API are still there to ease
the migration from Vert.x 3.

Whenever possible, Vert.x 4 APIs have been made available in Vert.x 3 with a deprecation of the old API, giving
the opportunity to improve a Vert.x 3 application with a better API while allowing the application to be ready for a Vert.x 4
migration.

<Cards columns={2}>
  <Card href="https://github.com/vert-x3/vertx-4-migration-guide/" title="Read migration guide">
    We provide a clear and documented migration path from Vert.x 3.9 to Vert.x 4.
  </Card>
  <Card href="https://www.manning.com/books/vertx-in-action" title="Vert.x in Action">
    Each sample in our book &ldquo;Vert.x in Action&rdquo; works with either Vert.x 3.9 or Vert.x 4.
  </Card>
</Cards>

## Vert.x 3 support

Vert.x 3 will continue to get bug fix releases officially until January 2023.

Vert.x is an open source project of the Eclipse Foundation, granting the community the opportunity to contribute
fixes beyond that deadline and possibly extend the support.
